Late blight is a major pain in the bum. I'm not aware of any organic controls and my understanding of the commercial non-organic controls are that they're complex to use, and from what I've read blight spores can travel tens of miles on the wind so they spread very easily.
Growing in a polytunnel or greenhouse are the only ways I've found to keep it at bay, neither of which are very practical when it comes to growing decent volumes of potatoes
I do still find that my polytunnel tomatoes get blight, but usually so late in the year that there's not a lot left cropping anyhow.
I discovered last year that blight needs a living host and it's therefore not a big deal to compost blight-affected plant material. It does mean that volunteer potatoes are a potential source of reinfection though, so I shall be extra-vigilant about getting rid of any that pop up this year.
James